In the art of submersible electrical motors, for example, of the type used in combination with a deep well water pump such as disclosed in U.S. Pat. No. 3,250,927, it is common for the motor to be submerged within the well water at a substantial depth. Electrical lead wires, commonly referred to as a "drop cable" extend from an external power source downwardly through the well casing to the electric motor. The motor may be provided with a power supply cord of predetermined length, and the drop cable is connected to the power supply cord by means of a splice or a molded-on cable connector, for example, of the type disclosed in U.S. Pat. No. 2,958,842. It is also common to provide the drop cable with a plug-type connector which is molded onto the lower end of the drop cable and plugs into a mating socket member supported within the submersible motor housing. For example, U.S. Pat. Nos. 3,059,210, 3,248,582, 3,294,993, 3,308,316, 3,350,587 and 3,777,194 disclose various forms of electrical plug-type connectors for a submersible electric motor.
It has been found highly desirable to eliminate the need for forming a splice or attaching an electrical plug-type connector to the lower end of electrical power supply lead wires or a drop cable and to eliminate the need for forming a positive liquid-tight seal at the splice or between the plug connector and the lead wires by means of injection molding the plug connector around the lead wires. By eliminating the plug connector, it is unnecessary for the motor and/or motor-pump manufacturer to supply a drop cable having a molded-on electrical plug member which mates with the socket member within the motor. Furthermore, the elimination of the plug-type connector eliminates the need for producing and supplying drop cables of various lengths corresponding to the depth of the motor-pump unit below the ground surface.
In view of the fact that electric motors submerged within a current conducting liquid such as well water are subjected to electrical grounding, it is desirable to protect the motor from a power or voltage surge, for example, as caused by lightning hitting the electrical power supply lines or drop cable. One form of lightning arrestor for a submersible electrical motor, is disclosed in U.S. Pat. No. 3,849,704. This arrestor incorporates an electrode within a gas generating, arc extinguishing material contained within a closed casing retained within the motor housing.